Pollen and seed production during mast years in hinoki cypress plantations in Kochi prefecture

Abstract

Pollen and seed production during mast years in hinoki cypress plantations in Kochi prefecture Pollen from the hinoki cypress causes an allergic reaction in many Japanese people, so it is important to understand the factors that affect pollen production in hinoki cypress plantations. Production of pollen cones and seed cones during the mast years of 2005 and 2014 was evaluated in hinoki cypress plantations of different stand density in two areas with different soil conditions in Kochi prefecture. Production of pollen cones and seed cones in 2014 was more than 3 times higher than that in 2005. The production was relatively high among reported values. Pollen cone production differed between the two areas and was not related to stand density. Seed cone production was not different between the two areas but was lower in the heavily thinned forest. The ratio of pollen cone production to seed cone production differed between the two areas and was lower in the heavily thinned forest. These results suggest that pollen cone production was affected by soil condition whereas seed production was relatively constant in relation to soil condition.